Moisture Ingression Effect on Stress Distributions in NCF-Bonded COG Packages

The objective of this paper is to investigate the effect of moisture ingression on stress field of the COG packages with NCF bonding. The coefficients of moisture diffusion and the hygro-strains of the NCF adhesive have been determined by an innovative approach of measuring the out-of-plane deformation of the bi-material specimens during moisture absorption at the condition of 30degC /85%RH using Twyman-Green interferometry, associated with a finite element analysis and bi-material theory. It can be concluded that the stress states of the NCF-bonded COG packages induced by transient moisture ingression have been fully addressed through experimental, theoretical and numerical approaches in this study.